The present invention relates to a treatment kit comprising:                a first implant comprising a first tubular body defining a window        a second implant comprising a second tubular body designed to be positioned in the window of the first tubular body to protrude relative to the first implant, the second implant comprising a retaining member retaining the second implant relative to the first implant;        a ring for retaining the second implant assembled on the first tubular body in the window and delimiting an insertion passage for the second implant.        
Such a kit is for example designed to be implanted in a cavity of a living being comprising a first conduit, and at least one branch protruding transversely from the first conduit. The cavity is for example a conduit for the circulation of a bodily fluid, such as a blood flow conduit.
In one example, the blood flow conduit is the aorta, in which a first implant is implanted. A second implant is deployed in an artery branched on the aorta, such as the iliac artery, the renal artery, the superior mesenteric artery, the coeliac artery and the supra-aortic arterial trunks, etc.
Alternatively, the first implant is designed to be positioned in the aortic arch. The second implant is then placed in one of the branches emerging in the aortic arch, such as the left common carotid artery, the left subclavian artery or the brachiocephalic arterial trunk.
Other applications are possible in the venous system, in particular in the inferior vena cava at the iliac bifurcation, at the anastomosis of the renal veins and the superior vena cava, at the anastomosis of its collateral branches.
Such a kit is generally implanted in a blood flow conduit to treat zones having defects or diseases, such as aneurysms or dissections.
In order to implant the kit, endoluminal techniques are currently preferred when they can be done. Indeed, these techniques are less invasive for the patient and reduce the mortality and morbidity levels, as well as the hospital stay time.
The endoluminal techniques provide excellent results to treat lesions in the descending thoracic aorta, which is linear. However, in the case of the aortic arch, implanting the kit using the endoluminal route presents some difficulties.
First, the first implant must be flexible enough to be able to adapt to the tortuosity of the arterial tree and curve to be brought into the aortic arch in a satisfactory manner, then deployed while conforming to the anatomy of that vessel.
Next, several secondary implants must be mounted transversely through windows arranged in the first implant. The role of these second implants is to fasten the first implant axially while avoiding the risk of migration, and to cover the supra-aortic arterial branches in order to ensure revascularization of those branches.
In order to deploy a kit as described above in a blood flow conduit having a branch, it is first known to release the first implant in the blood flow conduit. A window arranged in the first implant is positioned across from the source of each branch in which a second implant must be implanted. Then, the second implant is introduced into the window of the first implant through the branch.
The second implant is next deployed and is fixed on the first implant via at least one retaining member. The retaining member is for example a collar that can be radially deployed at one end of the second implant.
To ensure proper operation of the kit once it is implanted in the body, it is necessary to produce quasi-total sealing between the inner contour of the window arranged in the first implant and the outer contour of the second implant.
To that end, US 2006/0155359 describes a kit of the aforementioned type, in which the second implant comprises, at its end connected to the first implant, a double collar delimiting an annular throttle making it possible to receive the outer wall of the first implant. In this patent, the sealing is produced by the collars on the inner and outer faces of the main endoprosthesis by pressing the surfaces against one another.
Such a kit improves the sealing between the first implant and the second implant, in particular when the second implant is substantially perpendicular to the first implant.
However, in certain anatomical configurations, the second implant is inclined relative to a local axis of the first implant at the window, and is therefore not perpendicular to the axis. Furthermore, in some cases, the outer contour of the second implant is not conjugated with the inner contour of the window. The sealing between the first implant and the second implant cannot be done completely, which may lead to complications for the patient.